Yes - there is a creeping thyme called Elfin Thyme that is tiny enough to grow in cracks but it may not compete with established weeds and needs sandy soil. Another option is to fill in the cracks with a product called \"concrete crack filler\" sold at home center stores. It comes in a tube and you just squeeze it into cracks, it expands and there is no room for weeds. Keep growing, Marianne Binetti